Effects of azoxystrobin on wheat take-all

Abstract

Severity of take-all (Gaeumannomyces graminis var. tritici) on the roots of wheat was significantly decreased by foliar sprays of azoxystrobin in four of the six field experiments in which they were tested.  Decreases in plants with moderate or severe symptoms, compared with untreated, ranged from c 20% to more than 80%.  These effects on take-all were mostly associated with sprays at the full (250 g ai/ha) rate applied at relatively early growth stages (i.e. GS 31-32; beginning of stem extension) either alone or in combination with a later spray.

The effects of azoxystrobin on take-all are, however, somewhat variable.  Its current value as a tool in the practical management of the disease may, therefore, best be seen as providing a potential bonus in certain situations i.e. where applications at the rates and times at which it has so far mostly been tested and been shown to be effective against take-all, can be justified by its predicted effects on other diseases.

In one field experiment, a number of related compounds were also tested (all applied twice to the same plots) but there was no evidence that any of those currently available commercially had effects on take-all that were comparable to the effects of azoxystrobin.  An experimental compound had similar effects to azoxystrobin in the field experiment but, in contrast to azoxystrobin, had inconsistent effects when applied to the soil in pot experiments.